DE102019206784A1 - Method and arrangement for determining the state of a battery device - Google Patents

Abstract

A method and an arrangement (AO) for determining the state of a battery device (BV) with a number of battery cells (BZ) arranged inside a battery housing (GH) are disclosed. Two pressure values (d1, d2) that are redundant to one another are recorded in the interior of the battery housing (GH) using two mutually redundant pressure recording units (D1, D2). Two mutually redundant pressure gradients (g1, g2) are then determined from one of the two pressure values (d1, d2). The two pressure values (d1, d2) are then compared independently of one another with a predetermined pressure value threshold (ds1). Analogously, the two pressure gradients (g1, g2) are compared independently of one another with a predetermined pressure gradient threshold (gs1). If at least one of the first (d1) and second (d2) pressure values exceeds the first pressure value threshold (ds1) or at least one of the first (g1) and second (g2) pressure gradients exceeds the first pressure gradient threshold (gs1), a critical state is established in the Battery cells (BZ) recognized and changed as a measure at least one operating parameter in the battery device (BV).

Description

Technical area:

The present invention relates to a method and an arrangement for determining the status of a battery device with a number of battery cells arranged in the interior of a battery housing. The invention further relates to a battery device, in particular a traction battery device for an electrically driven vehicle, with a named arrangement.

State of the art and object of the invention:

Battery devices, especially traction battery devices for electrically powered vehicles, are known. Battery devices of this type generally have a multiplicity of battery cells which are arranged in a battery housing and are protected by the latter from external influences.

Lithium-ion battery cells or other battery cells with comparable properties are generally used as battery cells. Due to their nature, especially cell chemistry, such battery cells are susceptible to external influences, such as e.g. B. intense heat generation. In critical situations such as B. in the event of overheating, the battery cells can experience a so-called thermal runaway. In the event of a thermal runaway, individual components of the battery cells react with one another in an uncontrolled manner, generating intense heat and forming gas, which can lead to fire or explosion of the battery devices. In order to avoid this, a thermal runaway in the battery cells must be detected early and countermeasures initiated if necessary.

The object of the present application is therefore to provide a possibility for determining the state of a battery device with which, inter alia, a thermal runaway in battery cells of the battery device can be detected early and reliably.

Description of the invention:

This object is achieved by the subjects of the independent claims. Advantageous configurations are the subject of the subclaims.

According to a first aspect of the invention, a method for determining the state of a battery device, in particular a traction battery device of an electrically driven vehicle, with a number of battery cells arranged in the interior of a battery housing is provided.

According to the method, a first pressure value is detected in the interior of a battery housing by means of a first pressure detection unit (first detection of a first pressure value).

Here, the expression “first pressure value” is an umbrella term for one or more successively recorded (air) pressure measurement values of the first pressure recording unit.

Furthermore, a second pressure value in the interior of a battery housing is detected by means of a second pressure detection unit (second detection of a second pressure value).

Analogous to the expression “first pressure value”, the expression “second pressure value” is an umbrella term for one or more consecutively recorded (air) pressure measurement values of the second pressure recording unit.

A first pressure gradient is determined based on the first pressure value (first determination of a first pressure gradient).

The first pressure gradient is a change over time in the successively measured air pressure measurement values of the first pressure detection unit. To determine the first pressure gradient, two or more successively recorded pressure measurement values of the first pressure recording unit (“the first pressure value”) are used. If three or more pressure measurement values are recorded by the first pressure recording unit as “the first pressure value” and used to determine the first pressure gradient, then two or more pressure gradient values can be determined as “the first pressure gradient” from these pressure measurement values.

Analogously, a second pressure gradient is determined based on the second pressure value (second determination of a second pressure gradient).

The second pressure gradient is a change over time in the successively measured measured air pressure values of the second pressure detection unit. For the determination of the second pressure gradient, two or more successively recorded pressure measurement values of the second pressure recording unit (“the second pressure value”) are used. If three or more pressure measurement values are recorded by the second pressure recording unit as “the second pressure value” and used to determine the second pressure gradient, then two or more pressure gradient values can be determined as “the second pressure gradient” from these pressure measurement values.

The first and the second pressure value are then compared independently of one another with a first predetermined pressure value threshold (first Comparing the first and the second pressure value with a first predetermined pressure value threshold).

Here, all measured pressure values of the first pressure detection unit are compared one after the other with the first pressure value threshold. Analogously, all measured pressure values of the second pressure detection unit are compared one after the other with the first pressure value threshold.

Furthermore, the first and the second pressure gradient are compared with a first predetermined pressure gradient threshold (second comparison of the first and the second pressure gradient with a first predetermined pressure gradient threshold).

If several pressure gradient values were determined as “the first or the second pressure gradient” in the present steps “of determining the first or the second pressure gradient”, then all of these pressure gradient values can be compared independently and one after the other with the first pressure gradient threshold.

If at least one of the first and the second pressure value exceeds the first pressure value threshold, or if at least one of the first and the second pressure gradient exceeds the first pressure gradient threshold, a critical state is recognized in the battery cells (recognition of a critical state in the battery cells).

When the critical state is recognized, at least one of several operating parameters of the battery device is changed (changing at least one operating parameter in the battery device).

The at least one battery parameter is changed in such a way that the battery device or the battery cells leave the critical state and go into a non-critical state. If the critical state is caused, for example, by overheating in the battery cells, then the parameter change, for example, increases the cooling capacity of the battery device.

According to the method, two pressure values that are redundant to one another are recorded in the interior of the battery housing using two mutually redundant pressure recording units. Two mutually redundant pressure gradients are then determined from one of the two pressure values. The two pressure values are then compared independently of one another with a predetermined pressure value threshold. Analogously, the two pressure gradients are compared independently of one another with a predetermined pressure gradient threshold. If the first and / or the second pressure value exceed the first pressure value threshold and / or the first and / or the second pressure gradient exceed the first pressure gradient threshold, a critical state is recognized in the battery cells and at least one operating parameter in the battery device is changed as a countermeasure.

The invention makes use of gas formation in the interior of the battery housing, which occurs as a result of thermal runaway in the battery cells, in order to identify the thermal runaway and thus the faulty state in the battery cells at an early stage. Both the absolute air pressure (pressure value) and the temporal change in the absolute air pressure (pressure gradient) inside the battery housing are used to determine the values of which change rapidly as a direct consequence of gas formation inside the battery housing.

The above-described method has the advantage over a method in which the state of the battery cells is determined solely by detecting the development of heat or a change in capacity that a critical state can be determined promptly when the state changes to the critical state. In addition, the state can be determined reliably thanks to the use of two parameters, namely the absolute air pressure (pressure value) and the change in the absolute air pressure over time (pressure gradient).

To further increase the reliability of the determination of the state, two pressure values that are independent of one another are recorded for the absolute air pressure by two pressure recording units that act independently of one another and are each compared independently of one another with a predetermined pressure value threshold. Analogously, two pressure gradients are each determined from one of the two recorded pressure values and are also compared independently of one another with a predetermined pressure gradient threshold.

As a result, a double-redundant monitoring of the air pressure in the interior of the battery housing and thus a double-redundant or quadruple secured state determination of the battery device can be established.

The above-described method thus provides a possibility for determining the state of a battery device, with which a thermal runaway in battery cells of the battery device can be detected early and reliably.

E.g. the first and the second pressure value are also compared with a second predetermined pressure value threshold (third comparison of the first and the second pressure value with a second predetermined pressure value threshold). In addition, the first and the second pressure gradient are, for example, also compared with a second predetermined pressure gradient threshold (fourth comparison of the first and the second pressure gradient with a second predetermined pressure gradient threshold). If the first and the second pressure value exceed the second pressure value threshold and the first and the second pressure gradient also exceed the second pressure gradient threshold, a dangerous condition is recognized in the battery cells (recognition of a dangerous condition in the battery cells). When the dangerous state is recognized, at least the battery device is switched off (switching off the battery device).

If the battery device is installed, for example, as a traction battery in an electrically powered vehicle, corresponding further measures, such as, for. B. decommissioning and leaving the vehicle initiated.

E.g. it is also checked whether the first and the second pressure value are within a predetermined pressure value range (first check). If the first and / or the second pressure value are outside the pressure value range, an error signal is output which indicates that the first and / or the second pressure detection unit are faulty (output of an error signal).

With these steps, a plausibility check is carried out for the recorded pressure values or for the two pressure detection units, a check being made as to whether the pressure detection units are in a faulty state or whether the recorded pressure values can be used to determine the state.

E.g. it is also checked whether the first and the second pressure gradient are within a predetermined pressure gradient range (second checking). If the first and / or the second pressure gradient are outside the pressure gradient range, the error signal is output (output of the error signal).

With these steps, a plausibility check is carried out for the determined pressure gradients or for (pressure gradient) determination units, whereby it is checked whether the determination units are in a faulty state or whether the determined pressure gradients can be used for the state determination.

E.g. it is also checked whether a pressure value difference between the first and the second pressure value is within a predetermined pressure value difference range (third checking). If the pressure value difference lies outside the pressure value difference range, the error signal is output (output of the error signal).

E.g. it is also checked whether a pressure gradient difference between the first and the second pressure gradient is within a predetermined pressure gradient difference range. If the pressure gradient difference lies outside the pressure gradient difference range, the error signal is output (output of the error signal).

E.g. the step of the first recording further provides that the first pressure value is recorded as a first relative pressure value inside a battery housing to a pressure value in the vicinity of the battery housing.

Analogously, the step of the second recording also provides, for example, that the second pressure value is recorded as a second pressure value in the interior of a battery housing that is relative to the pressure value in the vicinity of the battery housing.

E.g. the steps of first and second detection, first and second determination, as well as first, second, third and fourth checking for a first predetermined period of time while the vehicle is stationary or after a second predetermined period of time has elapsed after a start carried out repeatedly on the vehicle. The steps of the first, the second, the third and the fourth comparison as well as the recognition, however, are only carried out after the expiry of the first period and only if the step of outputting the error signal was not carried out in the first period or in the the error signal was not given for the first time.

According to a second aspect of the invention, an arrangement for determining the status of a battery device, in particular a traction battery device of an electrically driven vehicle, with a number of battery cells arranged in the interior of a battery housing is provided.

The arrangement has a first pressure detection unit for detecting a first pressure value inside a battery housing, and a second pressure detection unit for detecting a second pressure value inside a battery housing. Furthermore, the arrangement has a first determination unit for determining a first pressure gradient based on the first pressure value, and a second determination unit for determining a second pressure gradient based on the second pressure value. In addition, the arrangement has a first comparison unit for comparing the first and of the second pressure value with a first predetermined pressure value threshold, and a second comparison unit for comparing the first and the second pressure gradient with a first predetermined pressure gradient threshold. The arrangement also has a detection unit which is set up to detect a critical state in the battery cells when at least one of the first and the second pressure value exceeds the first pressure value threshold; or at least one of the first and second pressure gradients exceeds the first pressure gradient threshold. Furthermore, the arrangement has a regulation / control unit which is set up to change at least one operating parameter in the battery device when the critical state is recognized.

According to a third aspect of the invention, a battery device, in particular a traction battery device for an electrically driven vehicle, is provided.

The battery device has a battery housing and a number of battery cells, wherein the battery cells are arranged in the interior of the battery housing and are protected by the battery housing from external influences in the vicinity of the battery housing. The battery device also has a previously described arrangement which is set up to determine the state of the battery device or the battery cells and to initiate appropriate measures in the event of a critical or dangerous state in the battery device or the battery cells.

Advantageous refinements of the method described above, insofar as they are otherwise transferable to the above-mentioned arrangement or the above-mentioned battery device, are also to be regarded as advantageous refinements of the arrangement or the battery device.

Figure list

• 1 in einer schematischen Darstellung einen Abschnitt einer Batterievorrichtung mit einer Anordnung zur Zustandsbestimmung der Batterievorrichtung gemäß einer beispielhaften Ausführungsform der Erfindung; und
• 2 in schematischen Ablaufdiagrammen ein Verfahren zur Zustandsbestimmung der Batterievorrichtung gemäß einer beispielhaften Ausführungsform der Erfindung.

In the following, exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings. Show:

• 1 in a schematic illustration a section of a battery device with an arrangement for determining the state of the battery device according to an exemplary embodiment of the invention; and
• 2 in schematic flowcharts a method for determining the state of the battery device according to an exemplary embodiment of the invention.

Detailed description of the drawings:

1 shows a schematic representation of a portion of a battery device BV with an arrangement AO for determining the state of the battery device BV .

2 shows a method for determining the state of the battery device in schematic flowcharts BV using the in 1 illustrated arrangement AO .

The battery device BV is designed, for example, as a traction battery device of an electrically powered vehicle.

The battery device BV has a battery case GH , a plurality of battery cells BZ, which are divided into several battery packs and connected in series and / or parallel to one another in the battery housing GH are arranged.

The battery case GH has at least one opening OF, through which gas inside the housing GH when there is overpressure inside the housing GH in the vicinity of the housing GH can escape and air from the environment at a negative pressure inside the housing GH into the housing GH can flow into it.

Lithium-ion battery cells or other battery cells with comparable properties are generally used as battery cells BZ. Because of their nature, especially cell chemistry, such battery cells BZ are susceptible to external influences, such as e.g. B. intense heat generation. In critical situations such as B. in the event of overheating, the battery cells BZ can experience a so-called thermal runaway. In the event of a thermal runaway, individual components of the battery cells BZ react with one another in an uncontrolled manner, generating intense heat and forming gas, which leads to a fire or explosion of the battery systems. In order to avoid this, there must be a thermal runaway in the battery cells BZ or the state of the battery device BV recognized at an early stage and countermeasures initiated.

To this end, the battery device BV the aforementioned arrangement AO for determining the state of the battery device BV or with the battery cells BZ.

The order AO has a first pressure detection unit D1 and a second pressure detection unit D2 which are each designed as a differential air pressure sensor.

The first pressure detection unit D1 each has an internal pressure measuring point for detecting an internal air pressure inside the battery housing GH and an external pressure measuring point for detecting an external air pressure in the vicinity of the battery case GH on. The first pressure detection unit D1 is set up to measure the inside and outside air pressure continuously or at regular time intervals, from the measured inside and outside air pressure an air pressure difference between the interior of the battery housing GH and the environment of the battery case GH to determine and the determined air pressure differential values as a first pressure value d1 to a first determination unit to be described below E1 and a first comparison unit, also to be described below V1 forward.

The second pressure detection unit D2 also has an internal pressure measuring point for detecting an internal air pressure inside the battery housing GH and an external pressure measuring point for detecting an external air pressure in the vicinity of the battery case GH on. The second pressure detection unit D2 is set up to measure the inside and outside air pressure continuously or at regular time intervals, from the measured inside and outside air pressure an air pressure difference between the interior of the battery housing GH and the environment of the battery case GH to determine and the determined air pressure differential values as a second pressure value d2 to a second determination unit to be described below E2 and the first comparison unit V1 forward.

The order AO further comprises the aforementioned first and second determination unit E1 , E2 which are formed, for example, in a microcomputer.

The first investigative unit E1 is on the signal input side with a signal output of the first pressure detection unit D1 connected in terms of signaling. The first investigative unit E1 is set up based on the first pressure value d1 that the determination unit E1 from the first pressure sensing unit D1 receives to determine a first pressure gradient g1 and the determined first pressure gradient g1 to a second comparison unit to be described below V2 forward.

The second investigation unit E2 is on the signal input side with a signal output of the second pressure detection unit D2 connected in terms of signaling. The second investigation unit E2 is set up based on the second pressure value d2 that the determination unit E1 from the second pressure sensing unit D2 receives to determine a second pressure gradient g2 and the determined second pressure gradient g2 to the second comparison unit V2 forward.

The order AO also has the aforementioned first and second comparison unit V1 , V2 each designed as a comparator, for example.

The first comparison unit V1 is on the signal input side with the signal output of the first pressure detection unit D1 and the signal output of the second pressure detection unit D2 connected in terms of signaling. The first comparison unit V1 is set up, the first pressure value d1 of the first pressure detection unit D1 and the second pressure value d2 of the second pressure detection unit D2 to compare independently of one another with a first predetermined pressure value threshold ds1 and with a second predetermined pressure value threshold ds2 and to forward the comparison result to a recognition unit K to be described below.

The second comparison unit V2 is on the signal input side with the signal output of the first determination unit E1 and the signal output of the second determination unit E2 connected in terms of signaling. The second comparison unit V2 is set up, the first pressure gradient g1 of the first determination unit E1 and the second pressure gradient g2 of the second determination unit E2 to compare independently of one another with a first predetermined pressure gradient threshold gs1 and with a second predetermined pressure gradient threshold gs2 and to forward the comparison result to the recognition unit K.

The order AO also has the aforementioned recognition unit K, which is designed, for example, as part of the aforementioned microcomputer.

The recognition unit K is on the signal input side with the signal output of the first comparison unit V1 and the signal output of the second comparison unit V2 connected in terms of signaling. The recognition unit K is set up based on the comparison results of the first and the second comparison unit V1 , V2 a critical condition or a dangerous condition in the battery cells BZ and thus in the battery device BV to recognize, and when such a critical or dangerous state is recognized, a corresponding signal is transmitted to a central regulating / control unit R to be described below.

The order AO also has the aforementioned central regulating / control unit R for controlling and regulating the battery device BV on, the signal input side with a signal output of the recognition unit K and one each Signal output of the first and the second comparison unit V1 , V2 is signal-connected.

The regulation / control unit R is set up, upon receipt of a signal from the detection unit K, which signals a critical state in the battery cells BZ, by changing at least one operating parameter in the battery device BV the operating state of the battery device BV to change and thus to defuse the critical condition. Furthermore, the regulation / control unit R is set up, when receiving a signal from the detection unit K, which signals a dangerous state in the battery cells BZ, the battery device BV switch off and initiate further suitable measures, whereby vehicle occupants of the vehicle and other persons from danger from the battery device BV to be protected.

After the arrangement AO for determining the state of the battery device BV with the help of 1 has been described in detail, the method for determining the state of the battery device will be described below BV with the help of 2 described in more detail.

• - Plausibilitätsprüfung der Fehlerfreiheit bei der Anordnung AO (Verfahrensabschnitt B); und
• - Erkennen von kritischen oder gefährlichen Zuständen bei der Batterievorrichtung BV und Einleiten von entsprechenden Maßnahmen (Verfahrensabschnitt C).

The process can roughly be divided into two following process sections B and C, namely:

• - Plausibility check of the correctness of the arrangement AO (Process section B); and
• - Detection of critical or dangerous states in the battery device BV and initiation of appropriate measures (procedural section C).

• - Erfassen von Druckwerten und Ermitteln von Druckgradienten (Verfahrensabschnitt A).

The two process sections B and C each require a preceding process section A or contain this process section A:

• - Acquisition of pressure values and determination of pressure gradients (method section A).

In method section A, the pressure value detection and pressure gradient determination SA1, SA2, SA3, SA4 are carried out, which are necessary for the following two method sections B and C.

The two procedural stages B and C are in 2 each illustrated with a view A and B.

In method section B it is checked whether the arrangement AO , especially the two pressure detection units D1 , D2 and the two investigation units E1 , E2 work properly or whether the pressure recording units D1 , D2 detected pressure values d1, d2 and those of the determination units E1 , E2 determined pressure gradients g1, g2 appear plausible.

Method section B or the plausibility check prevents that in the subsequent method section C or when determining critical or dangerous states in the battery device BV due to failure of one of the above-mentioned components of the arrangement AO to diagnose a fault in the battery device BV comes or an error-free diagnosis is made more difficult.

The basis for the plausibility check is the fact that due to the size of the battery housing GH and the opening on the housing GH as well as the usually constant ambient air pressure, the air pressure inside the housing GH cannot fall below or exceed a certain “plausible” pressure value range BD (or cannot exceed it over a longer period of time). A change in air pressure or the pressure gradient in the interior of the housing can correspondingly GH not (or not over a longer period of time) a certain “plausible” pressure gradient range BG fall below or exceed.

This fact is used for the plausibility check and that of the pressure recording units D1 , D2 detected pressure values d1, d2 and those of the determination units E1 , E2 Determined pressure gradients g1, g2 are checked for their plausibility.
The plausibility check is carried out when the vehicle is at a standstill or after a certain period of time has elapsed after the vehicle has been started (and before the vehicle is driven off) and thus after sufficient pressure equalization in the battery device BV performed for a first predetermined period of time.

For this purpose, the first pressure detection unit records D1 according to a method step SA1 in the manner described above a first pressure value d1 and forwards this to the first determination unit E1 and the first comparison unit V1 continue. In this case, a plurality of measured pressure values are measured at predetermined time intervals as the first pressure value d1 and forwarded together as the first pressure value d1.

The second pressure detection unit records analogously D2 according to a further method step SA2 also in the manner described above a second pressure value d2 and forwards this to the second determination unit E2 and the second comparison unit V2 continue. A plurality of measured pressure values are measured as the second pressure value d2 at the predetermined time intervals and forwarded together as the second pressure value d2.

The first investigative unit E1 determined according to a further method step SA3 from the transmitted first pressure value d1 or the corresponding measured pressure values a first pressure gradient g1 and forwards this to the second comparison unit V2 continue. The second determination unit determines analogously E2 in accordance with a further method step SA4, a second pressure gradient g2 is derived from the transmitted second pressure value d2 or the corresponding pressure measurement values and forwards this to the second comparison unit V2 continue.

The first comparison unit V1 checks, according to a further method step SB1, whether the first and the second pressure value d1, d2 or the measured pressure values are all within the specified “plausible” pressure value range BD. To this end, the first comparison unit compares V1 the first pressure value d1 and the second pressure value d2 independently of one another each with a lower and an upper threshold value of the pressure value range BD. If at least one of the first and the second pressure value d1, d2 lies outside the pressure value range BD, the first comparison unit gives V1 an error signal to the central regulation / control unit R, which signals that the arrangement AO is faulty.

The second comparison unit checks analogously V2 According to a further method step SB2, whether the first and the second pressure gradient g1, g2 are within the specified “plausible” pressure gradient range BG lie. To this end, the second comparison unit compares V2 the first pressure gradient g1 and the second pressure gradient g2 independently of one another, each with a lower and an upper threshold value of the pressure gradient range BG . If at least one of the first and the second pressure gradient g1, g2 lies outside the pressure gradient range BG so gives the second comparison unit V2 the error signal to the central regulation / control unit R from.

Optionally, a pressure value difference is calculated between the first and the second pressure value d1, d2 and it is checked whether this pressure value difference lies within a predetermined pressure value difference range. If the pressure value difference is outside the pressure value difference range, the error signal is sent to the central regulating / control unit R. Similarly, a pressure gradient difference is calculated between the first and the second pressure gradient g1, g2 and a check is made to determine whether this pressure gradient difference lies within a predetermined pressure gradient difference range. If the pressure gradient difference is outside the pressure gradient difference range, the error signal is also sent to the central regulating / control unit R.

These optional process steps are based on the fact that the two pressure detection units D1 , D2 or the two determination units E1 in the event of freedom from defects, pressure values d1, d2 or pressure gradients g1, g2 each have to deliver with a deviation below certain tolerance limits. The plausibility check enables random disruptive events or defects in one or another unit to be excluded.

If the regulating / control unit R receives at least one error signal during method steps SB1, SB2, it switches, for example, the entire battery device according to a further method step SB3 BV controls and sends an error message to, for example, a higher-level central vehicle control arrangement.

If the regulating / control unit R does not receive an error signal during method steps SB1, SB2, the arrangement repeats AO the above-mentioned steps SA1, SA2, SA3, SA4 and SB1, SB2 until an error signal is emitted or the above-mentioned first time period has expired.

If the first period of time has elapsed without an error signal being issued, the arrangement goes AO according to a further method step SB0 into method section C and now carries out the actual determination of the state of the battery device BV in which a critical or dangerous condition in the battery device BV is determined and, if necessary, appropriate countermeasures are initiated.

The status determination is usually carried out during the entire operating time of the vehicle. The method steps SA1, SA2, SA3 and SA4 for detecting pressure values d1, d2 and for determining pressure gradients g1, g2 are carried out in a manner analogous to the plausibility check (method section B).

The first comparison unit V1 compares according to a further method step SC1 the first and the second pressure value d1, d2 or the pressure measured values independently of one another with the first predetermined pressure value threshold ds1. If the pressure values d1, d2 fall below the first pressure value threshold ds1, the first comparison unit outputs V1 a “normal state” signal to the detection unit K, which signals that based on the pressure values d1, d2 neither critical nor dangerous State of the battery cells BZ or the battery device BV was established. If, on the other hand, at least one of the two pressure values d1, d2 exceeds the first pressure value threshold ds1, the first comparison unit outputs V1 a warning signal to the detection unit K, which signals that based on the pressure values d1, d2 a critical state in the battery cells BZ or in the battery device BV was established.

The second comparison unit compares analogously V2 according to a further method step SC2 the first and the second pressure gradient g1, g2 independently of one another, each with the first predetermined pressure gradient threshold gs1. If the pressure gradients g1, g2 fall below the first pressure gradient threshold gs1, the second comparison unit gives V2 a further “normal state” signal to the detection unit K, which signals that based on the pressure gradients g1, g2 no critical or no dangerous state in the battery cells BZ or in the battery device BV was established. If, on the other hand, at least one of the two pressure gradients g1, g2 exceeds the first pressure gradient threshold gs1, then the second comparison unit gives V2 a warning signal to the detection unit K, which signals that based on the pressure gradients g1, g2 a critical state in the battery cells BZ or in the battery device BV was established.

The recognition unit K receives it from the two comparison units V1 , V2 only "normal state" signals, it assumes a non-critical or non-dangerous state in the battery device BV and, according to a further method step SC0, causes the aforementioned steps SA1, SA2, SA3, SA4, SC1 and SC2 to be repeated. Furthermore, an error case is entered in an error information memory.

The recognition unit K receives it from the two comparison units V1 , V2 at least one warning signal, it is based on an at least critical state in the battery device BV and initiates the two comparison units V1 , V2 to compare the pressure values d1, d2 with a second pressure value threshold ds2, which is higher than the first pressure value threshold ds1, and the pressure gradients g1, g2 with a second pressure gradient threshold gs2, which is higher than the first pressure gradient threshold gs1.

The first comparison unit then compares V1 according to a further method step SC5, the first and the second pressure value d1, d2 independently of one another, each with the second pressure gradient threshold gs2. If the two pressure values d1, d2 fall below the second pressure value threshold ds2 or if only one of the two pressure values d1, d2 exceeds the second pressure value threshold ds2, the first comparison unit stops V1 the warning signal to the recognition unit K upright. If, on the other hand, the two pressure values d1, d2 exceed the second pressure value threshold ds2, the first comparison unit outputs V1 a danger signal to the detection unit K, which signals that based on the pressure values d1, d2 a dangerous state in the battery cells BZ or in the battery device BV was established.

The second comparison unit compares analogously V2 according to a further method step SC6, the first and second pressure gradients g1, g2 independently of one another, each with the second pressure gradient threshold gs2. If the two pressure gradients g1, g2 fall below the second pressure gradient threshold gs2 or if only one of the two pressure gradients g1, g2 exceeds the second pressure gradient threshold gs2, the second comparison unit stops V2 the further warning signal to the recognition unit K upright. If, on the other hand, the two pressure gradients g1, g2 exceed the second pressure gradient threshold gs2, the second comparison unit gives V2 a further danger signal to the detection unit K, which signals that, based on the pressure gradients g1, g2, a dangerous state in the battery cells BZ or in the battery device BV was established.

The recognition unit K receives it from the two comparison units V1 , V2 only two warning signals or one warning and one danger signal, it recognizes according to a further method step SC3 of a “only” critical state in the battery device BV and by outputting a corresponding warning signal to the regulation / control unit R, the regulation / control unit R, according to a further method step SC4, causes at least one operating parameter of the battery device BV to change and thus the battery device BV to "liberate" from the critical condition. Is the battery device BV Connected to a controllable / regulatable cooling circuit, the cooling capacity of the regulation / control unit R increases and thus reduces the operating temperature of the battery cells BZ. Alternatively, the regulation / control unit R reduces the power of the battery device BV and thus prevents a further rise in temperature and consequently a further rise in air pressure inside the battery case GH . Furthermore, according to method step SC3, the recognition unit K causes the aforementioned steps SA1, SA2, SA3, SA4, SC1, SC2, SC5 and SC6 to be repeated. In addition, an error case is entered in the error information memory.

The recognition unit K receives it from the two comparison units V1 , V2 According to a further method step SC7, it recognizes two danger signals of a dangerous state in the battery device BV and initiates the regulation / control unit R by sending a corresponding danger signal to the regulation / control unit R, the battery device according to a further method step SC8 BV completely shut down in a controlled manner and thus bring the vehicle to a standstill in a controlled manner. Furthermore, the regulation / control unit R informs the vehicle occupants by emitting a corresponding acoustic or optical warning signal to leave the vehicle as quickly as possible.

Claims (11)

Method for determining the status of a battery device (BV) with a number of battery cells (BZ) arranged inside a battery housing (GH), with the following steps: - First detection (SA1) of a first pressure value (d1) inside the battery housing (GH) by means of a first pressure detection unit (D1); - second detection (SA2) of a second pressure value (d2) inside the battery housing (GH) by means of a second pressure detection unit (D2); - first determining (SA3) a first pressure gradient (g1) based on the first pressure value (d1); - second determination (SA4) of a second pressure gradient (g2) based on the second pressure value (d2); - First comparison (SC1) of the first (d1) and the second (d2) pressure value with a first predetermined pressure value threshold (ds1); - a second comparison (SC2) of the first (g1) and the second (g2) pressure gradient with a first predetermined pressure gradient threshold (gs1); - First detection (SC3) of a critical state in the battery cells (BZ) when at least one of the first (d1) and the second (d2) pressure value exceeds the first pressure value threshold (ds1), or at least one of the first (g1) and the second (g2) pressure gradient exceeds the first pressure gradient threshold (gs1); - Changing (SC4) at least one operating parameter in the battery device (BV) when the critical state is recognized. Procedure according to Claim 1 , further comprising steps: third comparison (SC5) of the first (d1) and the second (d2) pressure value with a second predetermined pressure value threshold (ds2); - fourth comparison (SC6) of the first (g1) and the second (g2) pressure gradient with a second predetermined pressure gradient threshold (gs2); - Second detection (SC7) of a dangerous condition in the battery cells if the first (d1) and the second (d2) pressure value exceed the second pressure value threshold (ds2) and the first (g1) and the second (g2) pressure gradient exceed the second pressure gradient threshold ( exceed gs2); - Shutdown (SC8) of the battery device (BV) when the dangerous condition is detected. Procedure according to Claim 1 or 2 , further with steps: - first checking (SB1) whether the first (d1) and the second (d2) pressure value lie within a predetermined pressure value range (BD); - Output (SB3) of an error signal if the first (d1) and / or the second (d2) pressure value are outside the pressure value range (BD), the error signal indicating that the first (D1) and / or the second (D2) Pressure detection unit are faulty. Method according to one of the preceding claims, further comprising the steps: - Second checking (SB2) whether the first (g1) and the second (g2) pressure gradient lie within a predetermined pressure gradient range (BG); - Output (SB3) of the error signal when the first (g1) and / or the second (g2) pressure gradient are outside the pressure gradient range (BG). Method according to one of the preceding claims, further comprising the steps: - Third checking whether a pressure value difference between the first (d1) and the second (d2) pressure value lies within a predetermined pressure value difference range; - Output (SB3) of the error signal if the pressure value difference is outside the pressure value difference range. Method according to one of the preceding claims, further comprising the steps: - Fourth checking whether a pressure gradient difference between the first (g1) and the second (g2) pressure gradient lies within a predetermined pressure gradient difference range; - Output (SB3) of the error signal if the pressure gradient difference is outside the pressure gradient difference range. A method according to any one of the preceding claims, wherein: - the step of the first detection (SA1) further provides that the first pressure value (d1) is detected as a first relative pressure value inside a battery housing (GH) to a pressure value in the vicinity of the battery housing (GH); - the step of the second recording (SA2) further provides that the second pressure value (d2) is recorded as a second relative pressure value inside a battery housing (GH) to the pressure value in the vicinity of the battery housing (GH). Procedure according to Claim 6 or 7th , wherein the steps of first (SA1) and second (SA2) detection, first (SA3) and second (SA4) determination, as well as first (SB1), second (SB2), third and / or fourth Checking can be carried out repeatedly for a first predetermined period of time when the vehicle is stationary or after a second predetermined period of time has elapsed after the vehicle has been started. Procedure according to Claim 2 and one of the Claims 3 to 8th , the steps of the first (SC1), the second (SC2), the third (SC5) and the fourth (SC6) comparison as well as the first (SC3) and the second (SC7) recognition will take place after the expiry of the first period if the output step ( SB3) an error signal was not received. Arrangement (AO) for determining the status of a battery device (BV) with a number of battery cells (BZ) arranged in the interior of a battery housing (GH), comprising: - A first pressure detection unit (D1) which is set up to detect a first pressure value (d1) inside the battery housing (GH); - A second pressure detection unit (D2) which is set up to detect a second pressure value (d2) inside the battery housing (GH); - A first determination unit (E1) which is set up to determine a first pressure gradient (g1) based on the first pressure value (d1); - A second determination unit (E2) which is set up to determine a second pressure gradient (g2) based on the second pressure value (d2); - A first comparison unit (V1) which is set up to compare the first (d1) and the second (d2) pressure value with a first predetermined pressure value threshold (ds1); - A second comparison unit (V2) which is set up to compare the first (g1) and the second (g2) pressure gradient with a first predetermined pressure gradient threshold (gs1); - A detection unit (K) which is set up to detect a critical state in the battery cells (BZ) when at least one of the first (d1) and the second (d2) pressure value exceeds the first pressure value threshold (ds1), or at least one of the the first (g1) and the second (g2) pressure gradient exceeds the first pressure gradient threshold (gs1); - A regulation / control unit (R) which is set up to change at least one operating parameter in the battery device (BV) when the critical state is recognized. Battery device (BV), comprising: - a battery housing (GH); - A number of battery cells (BZ) arranged inside a battery housing (GH); - an order (AO) according to Claim 10 for determining the state of the battery device (BV).

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